DESCRIPTION: The development of an improved assay for genotoxicity is proposed. The assay will be based on the Unschedule DNA Synthesis assay that measures nucleotide incorporation due to repair of DNA damage. The proposal seeks to modify the assay to use non-radioactive tracers and flow cytometry. The successful completion of the proposed work will enable the applicant organization to provide an important new service to the chemical, cosmetic, consumer products and safety-testing industries. PROPOSED COMMERCIAL APPLICATION: MB Research will conduct this assay of genotoxicity (in-house) for members of the pharmaceutical, biotech, cosmetic, agrochemical, chemical and consumer products industries. Our clients are increasingly requesting rapid, reliable and inexpensive assays of genotoxicity (see letters from Brayer, Avon, and Perdue Pharma) that would be used to screen large numbers of chemicals. The results of such an assay would be used to determine which chemicals should be excluded from the product development process and which agents should move on to further tests of genotoxicity.